Quora: How Could We Stop an Asteroid?

asteroid impact
An artist’s impression of an asteroid impacting Earth. NASA/Don Davis

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Answer from Richard Muller, Professor of Physics at UC Berkeley, author of Now, The Physics of Time:

The best method for destroying a huge asteroid that is headed towards Earth that I've come across (in 37 years of thinking about this problem) is to explode a thermonuclear warhead a few miles above the surface. If done properly, the bomb would not break up the asteroid, but it would vaporize anything volatile on the surface (such as ice or methane). As these blew off they would provide a gentle and fairly uniform push to deflect the asteroid. It's easier for a comet than for an asteroid. I explained this method in my first book, published in 1988, Nemesis: The Death Star (available used on Amazon).

When I saw the (then new) movie Armageddon, I watched the scientists trying to figure out what to do. Then they decide to explode a bomb on the surface of the asteroid, blowing it to smithereens. NO! NO! I shouted (in my head). Haven't you read my book?!! You'll just turn a bullet into shotgun shrapnel, doing more damage than the single impact would have done! It turned out, of course, that I was right. The scientists should have first checked the literature, not simply made up a new idea just because it sounded good and used it without peer review.

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The warhead could be one (or several) from our existing fleet of intercontinental ballistic missiles. We would just have to reprogram their flight paths, and their detonation program. These weapons typically explode before they reach the surface, in order to inflict maximum damage in a war, so the modifications should not be difficult. The multiple warheads don't need to be detonated simultaneously, since the deflections can be quite small.

The problem, of course, is that we really should test such an approach before we try it. Right now that is impossible, since international treaties prohibit nuclear weapons in space. However, if an asteroid were predicted to hit the Earth, then there might be time to agree to an exception to the treaty, both to make a test (on a distant non-threatening asteroid) and to do the actual deflection. There is great value in doing the deflection early, when a small change in orbit would cause the asteroid to miss.

If there is a huge asteroid capable of destroying Earth that is going to hit us, how would we attempt to stop it (2017)? originally appeared on Quora - the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google+. More questions:

Quora: How Could We Stop an Asteroid? | Opinion